Potassium lockout or Cal/Mag issue?

S

Sascwatch

New Member
Got a good look at another garden and he's got an issue affecting the older mature leaves. New growth looks awesome and plants are growing nice.

Plants are 3 weeks into veg
Temps are 19c at night and 25c lights on
Medium is PROMIX HP
Feeding is done at 5.8ph
Feed @5.8- water @6.0 feed @5.8 repeat
Calmag has been used with every feeding at 5ml per gallon

I'm thinking calmag has been overdone a bit and is causing potassium to be locked out. I would like to fix this before the switch to 12/12

Will post some pics in a minute.
 
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I would guess you are using RO water because of the 5 ml of cal mag per gallon of water??you can check the run off water for PPM to see if its starting to run high and needs to be flushed? and the run off water PH to see what it is in the soil I think it should be halfway between the PH number you put in and what PH comes out ,is your soil PH hope that made sense??so if your soil ph is too low then switch it up and ph your water at 6.5 to raise the soil level ph, what PPM are you feeding at .just throwing some things out their .:lot-o-toke:
 
Water in @5.8 measured run off @ about 6 plus or minus .1 depending on the plant. Plants were flushed 2 weeks prior so they've been watered 3 times, 2 of which were feed.

I'm leaning towards to much calmag, regular city water. Cutting out the calmag for a few feeds to see what happens. Substitute calmag for Epsom salts maybe on some feeds?
 
Since you are adding calmag, and still have what looks like a magnesium issue, it has to be pH. Promix being a peat based soilless medium, is very acidic. Flushing regularly to remove broken down peat is probably a good idea, but raising the pH of your incoming fluids will also work. Get it up there to the 6.2 or so range, and see if that is enough to start picking up the magnesium... you might have to go even higher than that.
 
Sascwatch said:
Got a good look at another garden and he's got an issue affecting the older mature leaves. New growth looks awesome and plants are growing nice.

Plants are 3 weeks into veg
Temps are 19c at night and 25c lights on
Medium is PROMIX HP
Feeding is done at 5.8ph
Feed @5.8- water @6.0 feed @5.8 repeat
Calmag has been used with every feeding at 5ml per gallon

I'm thinking calmag has been overdone a bit and is causing potassium to be locked out. I would like to fix this before the switch to 12/12

Will post some pics in a minute.
Click to expand...

A little late but the added cal-mag with already high background EC "city water" was prob causing lockout... get rid of cal-mag and get hold of some hard water nutes.
 
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